From tapping into a solar initiative, California's multibillion-dollar effort to increase the use of photovoltaic systems, to installing state-of-the-art lighting, Stillings is leading a center determined to become a focus for those seeking to reduce their energy impact on the planet and save money through energy-efficiency investments.
The center's programs include giving away trees for their environmental benefit and free conservation workshops. It also runs a library that lends energy-diagnostic equipment.
Stillings was living in San Diego and consulting for the energy industry after more than two decades of working for New York State Electric & Gas when she was tapped to head the center in 2002.
It wasn't all that long ago, Stillings said, that advocating for conservation and energy efficiency were much more difficult.
"We've gone from feeling like we were a voice in the wilderness to this exciting point now," Stillings said. "The increasing awareness of the public is a validation of what we were talking about all along."
Growing awareness is surely a positive trend, but could all the negatives - melting ice caps, new coal-burning power plants in China and the continued purchase of gas-guzzling vehicles by Americans - get her discouraged?
"Not at all," she said.
"Survey data says that 80 percent of Californians are concerned about global warming, but 50 percent say they don't know what to do about it," she said. "There is no reason for pessimism. We have the ability to find solutions to the problem."
Stillings grew up in the New York City suburb of Mount Vernon in a family hit hard by the Great Depression. She won a science scholarship to the University of Rochester, but it didn't take long for her to conclude that she was more a people person than a science type.
After college, she raised a family and, later, parlayed her passion for scuba diving into a retail dive shop in Binghamton, N.Y. Owning that small business, Stillings said, was a serious education in the importance of customer service.
The education was of great use at New York Electric & Gas, which had alienated customers by imposing a 30 percent rate hike to pay for a nuclear power plant. Stillings said she strove to be compassionate and to educate customers about energy.
She believed that education could not start too young, so she helped launch the first energy program in New York for elementary school students. She helped introduce large-type bills and a newsletter for senior citizens, along with a host of other customer-outreach programs.
"I even brought in social workers to help senior citizens pay their bills," Stillings said.
Moving up through the company's ranks, she was named vice president of marketing and sales, smashing through several "glass ceilings" along the way - including being the utility's first woman manager and first woman executive.
She consulted for a few years before being chosen as director of the energy center in San Diego.
John Moot, chairman and president of the center's board, said the board selected Stillings because she had long experience in the utility industry and was familiar with programs that benefit the public.
Stillings understands the need to diversify the center's funding sources - 95 percent of its income comes from utility bill charges - and has made it a priority to expand grants and private funding, Hoffmann said.
Stillings also is determined to maintain the center as an independent energy-resource center, believing that the public has more confidence with obtaining these services from that type of office rather than a local utility.
Michael Shames, executive director of the Utility Consumers' Action Network, said he personally likes Stillings but believes she has focused too much on the "big picture" and not enough on the nitty-gritty of energy policy.
"She has never had a command of the details, and it renders her less effective," said Shames, who was among those who advocated for the center's creation.
He would have preferred that the center take a more aggressive approach in promoting alternative energy, with less emphasis on the purely educational.
"I would have hoped it was more involved in things like structuring utility rates, which can thwart innovation and new technologies," he said.
Stillings believes the center has positioned itself as a trustworthy program administrator, which the public sees differently than the local utility, whose primary mission is to earn money for its shareholders.
After decades in the energy business, moreover, Stillings said her passion for sustainable energy feels renewable.
"My oldest friends have retired to Florida," she said. "But I don't know if I'll ever retire."